Controls on Land Surface Temperature along a Gradient of Managed Land-Cover Types in Central Virginia

Changes in land-cover, land-use, and land-management (LULMLCC) can have significant effects on local and global climate. However, the direction and magnitude of the influence of LULC on surface temperature is less well understood in the temperate biome, where significant land management occurs, than in tropical or boreal biomes. This uncertainty is compounded in managed ecosystems that experience frequent land-cover, land-use and land-management (LULMLCC) interventions.

To examine the effects of LULMLCC on climate in the temperate biome, we established a cluster of three eddy flux towers that are co-located (1.5 km apart) in central Virginia along a gradient of land-use and land-management: a loblolly pine stand (US-SB1), a recently clear-cut loblolly stand (US-SB3) and a switchgrass field (US-SB2) used for bioenergy.

We found that, when averaged annually the clear-cut had the highest daytime temperature followed by the switchgrass field and pine stand. In contrast, patterns in nighttime temperatures are reversed, the pine stand had the warmest nighttime temperatures followed by switchgrass, and clear-cut. Additionally, we found strong seasonal differences in surface temperature between the pine and switchgrass land-cover types. In the growing seasons, pine and grass had similar daily temperatures despite higher net radiation in pine. In the winter, the pine ecosystem had higher daily temperatures. During low canopy periods in the switchgrass (immediately after fall harvest and just before spring emergence), the switchgrass daily temperatures were significantly, but temporarily higher than the pine stand, highlighting potential interactions between available energy and canopy density on surface temperature.

Finally, we evaluate the drivers of these diurnal and intra-annual dynamics using established temperature attribution metrics and examine the relationship between surface temperature, incoming radiation, and leaf-area index. Overall, our results highlight the importance of seasonality and management activities when quantifying LULMLCC influences on climate in temperate biomes.